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Hallinan G, Littlefair SP, Cotter G, Bourke S, Harding LK, Pineda JS, Butler RP, Golden A, Basri G, Doyle JG, Kao MM, Berdyugina SV, Kuznetsov A, Rupen MP, Antonova A. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence. Nature 2015. [PMID: 26223623 DOI: 10.1038/nature14619] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs.
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Affiliation(s)
- G Hallinan
- California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - S P Littlefair
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
| | - G Cotter
- Department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
| | - S Bourke
- California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - L K Harding
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-0899, USA
| | - J S Pineda
- California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - R P Butler
- Centre for Astronomy, National University of Ireland, Galway, University Road, Galway, Republic of Ireland
| | - A Golden
- Department of Mathematical Sciences, Yeshiva University, New York, New York 10033, USA
| | - G Basri
- Astronomy Department, University of California, Campbell Hall, Berkeley, California 94720, USA
| | - J G Doyle
- Armagh Observatory, College Hill, Armagh BT61 9DG, UK
| | - M M Kao
- California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - S V Berdyugina
- Kiepenheuer Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg, Germany
| | - A Kuznetsov
- Institute of Solar-Terrestrial Physics, Irkutsk 664033, Russia
| | - M P Rupen
- National Radio Astronomy Observatory, PO Box O, Socorro, New Mexico 87801, USA
| | - A Antonova
- Department of Astronomy, Faculty of Physics, St Kliment Ohridski University of Sofia, 5 James Bourchier Boulevard, 1164 Sofia, Bulgaria
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Carilli CL, Bertoldi F, Menten KM, Rupen MP, Kreysa E, Fan X, Strauss MA, Schneider DP, Bertarini A, Yun MS, Zylka R. Dust Emission from High-Redshift QSOs. Astrophys J 2000; 533:L13-L16. [PMID: 10727380 DOI: 10.1086/312588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2000] [Accepted: 02/28/2000] [Indexed: 05/23/2023]
Abstract
We present detections of emission at 250 GHz (1.2 mm) from two high-redshift QSOs from the Sloan Digital Sky Survey sample using the bolometer array at the IRAM 30 m telescope. The sources are SDSSp 015048.83+004126.2 at z=3.7 and SDSSp J033829.31+002156.3 at z=5.0; the latter is the third highest redshift QSO known and the highest redshift millimeter-emitting source yet identified. We also present deep radio continuum imaging of these two sources at 1.4 GHz using the Very Large Array. The combination of centimeter and millimeter observations indicate that the 250 GHz emission is most likely thermal dust emission, with implied dust masses approximately 108 M middle dot in circle. We consider possible dust heating mechanisms, including UV emission from the active galactic nucleus (AGN) and a massive starburst concurrent with the AGN, with implied star formation rates greater than 103 M middle dot in circle yr-1.
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Bartel N, Bietenholz MF, Rupen MP, Beasley AJ, Graham DA, Altunin VI, Venturi T, Umana G, Cannon WH, Conway JE. The changing morphology and increasing deceleration of supernova 1993J in M81. Science 2000; 287:112-6. [PMID: 10615042 DOI: 10.1126/science.287.5450.112] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Twenty consecutive Very Long Baseline Interferometry images of supernova 1993J from the time of explosion to the present show the dynamic evolution of the expanding radio shell of an exploded star. High-precision astrometry reveals that the supernova expands isotropically from its explosion center. Systematic changes in the images may reflect a pattern of anisotropies and inhomogeneities in the material left over from the progenitor star. As the shock front sweeps up the material in the surrounding medium, it is increasingly decelerated and influenced by the material. After 5 years, the supernova has slowed to half of its original expansion velocity and may have entered the early stages of the adiabatic phase common in much older supernova remnants in the Milky Way Galaxy.
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Affiliation(s)
- N Bartel
- Department of Physics and Astronomy, York University, Toronto M3J 1P3, Ontario, Canada. National Radio Astronomy Observatory, Socorro, NM 87801, USA. Max-Planck-Institut fur Radioastronomie, D-53121 Bonn, Germany. Jet Propulsion Laboratory, Cali
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Fan X, Strauss MA, Gunn JE, Lupton RH, Carilli CL, Rupen MP, Schmidt GD, Moustakas LA, Davis M, Annis J, Bahcall NA, Brinkmann J, Brunner RJ, Csabai I, Doi M, Fukugita M, Heckman TM, Hennessy GS, Hindsley RB, Ivezic Z, Knapp GR, Lamb DQ, Munn JA, Pauls AG, Pier JR, Rockosi CM, Schneider DP, Szalay AS, Tucker DL, York DG. The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data. Astrophys J 1999; 526:L57-L60. [PMID: 10550277 DOI: 10.1086/312382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.
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Abstract
Very-long-baseline radio interferometry images of the nuclear region of the nearby spiral galaxy M81 reveal the most compact galactic core outside the Galaxy of which the size has been determined: 700 x 300 astronomical units (AU). The observations exclude a starburst or supernova interpretation for the core. Instead they favor an active galactic nucleus. There is evidence for a northeastern jet bent by approximately 35 degrees over a length scale from 700 to 4000 AU. The jet is, on average, directed toward an extended emission region, probably a radio lobe, about 1 kiloparsec (kpc) away from the core. A corresponding emission region was found in the southwest at a distance of only 30 pc from the core. The observed jet is extremely stable and likely to be associated with a steady-state channel. There is no detectable motion along the jet beyond the nominal value of -60 +/- 60 km.s-1. The level of activities in the core region of M81 is intermediate between that of SgrA* and that of powerful radio galaxies and quasars.
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Affiliation(s)
- N Bartel
- Department of Physics and Astronomy, York University, North York, ON, Canada
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Harmon BA, Wilson CA, Zhang SN, Paciesas WS, Fishman GJ, Hjellming RM, Rupen MP, Scott DM, Briggs MS, Rubin BC. Correlations between X-ray outbursts and relativistic ejections in the X-ray transient GRO J1655 – 40. Nature 1995. [DOI: 10.1038/374703a0] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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